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Dual-purpose corneal tissue for anterior lamellar keratoplasty and Descemet’s membrane endothelial keratoplasty
Abstract
Objective:
To assess the intraoperative issues and surgical outcomes of preparing a single-donor corneal tissue for same-day use in both deep anterior lamellar keratoplasty (DALK) and Descemet's membrane endothelial keratoplasty (DMEK).
Design:
Consecutive retrospective case series.
Participants:
Ten eyes of 10 patients who underwent DALK (5 patients) or DMEK (5 patients) surgery using dual-purpose corneal tissue.
Methods:
Five dual-purpose corneoscleral rims were used to prepare tissue for 5 DMEK and 5 DALK procedures. The submerged cornea using backgrounds away technique was first used to harvest the 5 DMEK grafts, and the remaining tissue was used for the 5 DALK grafts. Tissue preparation and operative use occurred on the same day. Tissue preparation challenges, intraoperative complications, and visual recovery were assessed.
Results:
There were no difficulties in preparing the 5 dual-purpose tissues, and all 10 lamellar transplants were completed successfully. At the 6-month follow-up, the mean best-corrected distance visual acuity improved from 20/250 to 20/80 in the DALK patients, and from 20/300 to 20/25 in the DMEK patients. Postoperative complications after DALK included retained viscoelastic agent at the interface in 1 patient and a double anterior chamber managed with rebubbling in another. After DMEK, a peripheral partial graft detachment occurred in 1 patient and was managed successfully with rebubbling. All corneas demonstrated clarity on slit-lamp examination.
Conclusions:
Single-donor corneal tissue can be effectively used for both DALK and DMEK, and may represent a more efficient use of corneal tissue. Complications with the preparation of dual-purpose tissue were not encountered.
... The concept of the splitting of donor corneal tissue for dual purpose was previously described. [18][19][20] In 2 of these methods (contact lens assistant and submerged cornea using backgrounds away technique), marking the stromal side to facilitate with graft orientation is not possible. 18,19 The disadvantages of the splitting method described by Heindl et al 20 are the longer time it takes to create the scroll and the fact that the anterior cornea and the DMEK graft have to be at the same size. ...
... [18][19][20] In 2 of these methods (contact lens assistant and submerged cornea using backgrounds away technique), marking the stromal side to facilitate with graft orientation is not possible. 18,19 The disadvantages of the splitting method described by Heindl et al 20 are the longer time it takes to create the scroll and the fact that the anterior cornea and the DMEK graft have to be at the same size. In our study, 26 eyes of 26 patients underwent DMEK using the viscoelastic marking technique. ...
Purpose:
To describe the viscoelastic marking technique, a novel marking technique of Descemet membrane endothelial keratoplasty (DMEK) grafts that enables usage of a single donor cornea for 2 surgeries-one that uses Descemet membrane and endothelium (DMEK) and the other using the stroma and Bowman layer.
Methods:
A retrospective case analysis was performed on 26 eyes of 26 consecutive patients who underwent DMEK using the "viscoelastic marking technique." In this novel technique, an ophthalmic viscoelastic device (Healon 5) is placed over the endothelial side. Descemet membrane is then folded in half over the ophthalmic viscoelastic device with the stromal side up, and the F mark is drawn on the stromal side of the folded Descemet membrane. Primary outcome was best spectacle-corrected visual acuity, and secondary outcomes included graft detachment and rebubble rate, graft failure, and endothelial cell density.
Results:
Mean best spectacle-corrected visual acuity improved significantly from 1.0 ± 0.7 logarithm of the minimum angle of resolution (LogMAR) before the surgery to 0.9 ± 0.7 LogMAR, 0.5 ± 0.6 LogMAR, 0.4 ± 0.2 LogMAR, and 0.4 ± 0.4 LogMAR at 1, 3, 6, and 12 months after surgery, respectively. Seven eyes (27%) had partial graft detachment that required air injection. Primary failure occurred in 3 eyes (11%). There were no free-floating donors or recognized inverted donors. The endothelial cell density loss at 12 months after surgery was a cell-loss rate of 38.3%.
Conclusions:
The viscoelastic marking technique is a simple, approachable, and safe technique for marking DMEK grafts while preserving the anterior cornea for additional surgery.
... However, this practice results in underutilisation of the remaining layers of corneal tissue, which is disconcerting given the scarcity of available donor tissue. In contrast, this technique is more commonly practiced in other countries such as Germany [12], India [13], and Canada [14]. ...
... Several studies have demonstrated that the split use of donor corneal tissue for both DALK and DMEK procedures is feasible. 6,7,12,13 Because corneal thickness and stiffness are positively correlated, the residual, thinner graft from preparing DSAEK donor tissue, compared with the thicker graft from preparing DMEK donor tissue, is considered more fragile and less biomechanically stable; however, only 1 study reported the successful combination of DALK and DSAEK. 8 Our study aims to demonstrate its safety. ...
Purpose
To evaluate the outcomes of divided residual donor corneas obtained from endothelial keratoplasty in keratoconus with deep anterior lamellar keratoplasty (DALK).
Methods
In this retrospective, comparative, clinical study, 103 keratoconic eyes that underwent DALK were enrolled; 67 eyes received thin grafts from Descemet stripping automated endothelial keratoplasty, and 36 received thick grafts from Descemet membrane endothelial keratoplasty. Baseline and postoperative central corneal thickness (CCT), inferior corneal thickness, uncorrected distance visual acuity, corrected distance visual acuity, corneal astigmatism, mean keratometry, biomechanical properties, and complication rates were measured.
Results
Six months after transplantation, the group receiving thin grafts had a CCT of only 455.1 ± 43.0 μm, whereas that of the group receiving thick grafts was 546.7 ± 44.2 μm. Both CCT and inferior corneal thickness in the thin group were significantly lower than those in the thick group (measured with Pentacam at 36 months, P < 0.001) and remained throughout the 5-year follow-up period. Both procedures had comparable postoperative logarithm of the minimum angle of resolution UDVAs, logarithm of the minimum angle of resolution corrected distance visual acuity, astigmatism, and mean keratometry values (36 months; P = 0.335, 0.286, 0.680, and 0.365, respectively). Corneal biomechanical analysis revealed that the thin group had a significantly higher stiffness parameter at the first applanation than the thick group at the 2-year follow-up ( P = 0.036) while other parameters were equivalent.
Conclusions
The outcomes of keratoplasty with donor tissue are comparable regardless of the thickness of the graft, which suggests that transplantation with either type of the split corneal procedure for DALK in patients with keratoconus is feasible.
Purpose:
The purpose of this study was to describe a novel bandage contact lens (BCL) interface technique for marking the Descemet membrane endothelial keratoplasty (DMEK) graft so that a single donor cornea can be used effectively for 2 recipients during acute shortage.
Methods:
This was a retrospective comparative case series. In group A, 37 eyes underwent DMEK using a graft marked by the ‟BCL interface technique" that was compared with 49 conventional DMEK grafts marked through the stromal window (group B). In group A, a resized BCL with a central 3-mm hole with the concavity up was placed between the stroma and peeled-off DM. This BCL with DM was flipped for S-stamping on the DM side. Final trephination was performed on a second Teflon block. The remaining anterior lamellar tissues of group A were used on the same day for other keratoplasty procedures. Endothelial cell density (ECD) and endothelial cell loss between the 2 groups were compared after 3 and 6 months.
Results:
The ECD at 3 months in group A (n = 35) versus group B (n = 45) was 2228 ± 270/mm2 versus 2302 ± 254/mm2 (P = 0.48), and the ECD at 6 months (n = 23 and 22) was 2058 ± 324/mm2 versus 2118 ± 260/mm2 (P = 0.72). The corresponding endothelial cell loss was 23.3% ± 6.8% versus 20.3% ± 6.1% (P = 0.18) at 3 months and 29.1% ± 8.4% versus 26.7% ± 8.0% (P = 0.34) at 6 months. Among anterior tissues of group A, 17 (45.9%) were used for deep anterior lamellar keratoplasty, 18 (48.6%) were used for larger therapeutic and tectonic grafts, and 2 were used as keratoprosthesis carriers. Donor detachment rate (8.6% vs. 8.9%) was similar in both groups without primary graft failures.
Conclusions:
The BCL interface technique is a simple and safe technique for stamping DMEK grafts. Anterior corneal tissues can be used for additional keratoplasties during donor shortage.
Purpose:
Corneal transplantation is the most frequently performed transplant procedure. In much of the world, the demand for donor tissue heavily outstrips supply. With developments within lamellar corneal graft surgery, the use of split corneal donor tissue to increase donor tissue supply seems a pragmatic solution to reduce the supply and demand mismatch. This is especially important with tissue supply expected to be affected by the COVID-19 pandemic.
Methods:
A literature review of techniques was performed, enabling multiple transplants to be derived from a single donor and simulation of a model to quantify the number of corneas potentially saved.
Results:
Studies on splitting corneal donor tissue have demonstrated that up to 5 recipients may benefit from 1 donor scleral button. The impact of splitting donor tissue may provide a saving of up to 25.3% of donor graft tissue.
Conclusions:
Splitting and preparing the donor tissue within an eye bank will improve tissue validation and donor tissue availability and may increase surgeon efficiency.
Human corneal endothelium has long been thought to be a non-mitotic cell layer with no endogenous reparative potential. Pathologies that damage endothelial function result in corneal decompensation and, if untreated, blindness. The mainstay of treatment involves partial or complete corneal replacement, amounting to 40% of all corneal transplants performed worldwide. We summarize the case reports describing complications post-operatively in the form of (sub)total graft detachment and those resulting in post-operative bare stroma. Complications during cataract and glaucoma surgery leading to an uncovered posterior cornea are also included. We discuss the newer treatment strategies that are alternatives for current DMEK and DSAEK surgery, including partial grafts and stripping of the diseased cell layer. In more than half of the cases reviewed, corneal transparency returned despite incomplete or no corneal endothelial cell transplantation. We question the existing paradigm and concerning corneal endothelial wound healing in vivo. The data support further clinical study to determine the safety of simple descemethorexis in central endothelial pathologies, such as Fuchs, where presence of healthy peripheral cells may allow successful corneal recompensation without the need for donor cells.
Corneal transplantation or keratoplasty has developed rapidly in the past 10 years. Penetrating keratoplasty, a procedure consisting of full-thickness replacement of the cornea, has been the dominant procedure for more than half a century, and successfully caters to most causes of corneal blindness. The adoption by specialist surgeons of newer forms of lamellar transplantation surgery, which selectively replace only diseased layers of the cornea, has been a fundamental change in recent years. Deep anterior lamellar keratoplasty is replacing penetrating keratoplasty for disorders affecting the corneal stromal layers, while eliminating the risk of endothelial rejection. Endothelial keratoplasty, which selectively replaces the corneal endothelium in patients with endothelial disease, has resulted in more rapid and predictable visual outcomes. Other emerging therapies are ocular surface reconstruction and artificial cornea (keratoprosthesis) surgery, which have become more widely available because of rapid advances in these techniques. Collectively, these advances have resulted in improved outcomes, and have expanded the number of cases of corneal blindness, which can now be treated successfully. Femtosecond-laser-assisted surgery, bioengineered corneas, and medical treatment for endothelial disease are also likely to play a part in the future.
To evaluate the relative risk of immunologic rejection episode in patients who underwent Descemet's membrane endothelial keratoplasty (DMEK), Descemet's stripping endothelial keratoplasty (DSEK), and penetrating keratoplasty (PK).
Comparative case series.
One hundred forty-one eyes treated with DMEK at Price Vision Group, Indianapolis, Indiana.
The patients in the DMEK group were compared retrospectively with cohorts of DSEK (n = 598) and PK (n = 30) patients treated at the same center, with similar demographics, follow-up duration, and indications for surgery. The postoperative steroid regimen and rejection criteria were identical in the 3 groups. Kaplan-Meier survival analysis, which takes varying length of follow-up into consideration, was performed to determine the cumulative probability of a rejection episode 1 and 2 years after surgery. Proportional hazards analysis was used to determine the relative risk of rejection episodes between the 3 groups. P<0.05 was considered significant and calculated using the log-rank test.
Rejection-free survival and cumulative probability of a rejection episode.
The mean recipient age was 66 years (56% females and 94% Caucasian) and median follow-up duration was 13 months (range, 3-40) in the DMEK group. Fuchs' dystrophy was the most common indication for surgery (n = 127; 90%) followed by pseudophakic bullous keratopathy (n = 4; 4%) and regrafts (n = 9; 6.4%). Only 1 patient (0.7%) had a documented rejection episode in the DMEK group compared with 54 (9%) in the DSEK and 5 (17%) in the PK group. The Kaplan-Meier cumulative probability of a rejection episode at 1 and 2 years was 1% and 1%, respectively, for DMEK; 8% and 12%, respectively, for DSEK; and 14% and 18%, respectively, for PK. This was a highly significant difference (P = 0.004). The DMEK eyes had a 15 times lesser risk of experiencing a rejection episode than DSEK eyes (95% confidence limit [CL], 2.0-111; P = 0.008) and 20 times lower risk than PK eyes (95% CL, 2.4-166; P = 0.006).
Patients undergoing DMEK had a significantly reduced risk of experiencing a rejection episode within 2 years after surgery compared with DSEK and PK performed for similar indications using the same corticosteroid regimen.
To evaluate the feasibility of split cornea transplantation for 2 recipients by combining deep anterior lamellar keratoplasty (DALK) and Descemet membrane endothelial keratoplasty (DMEK).
Interventional case series.
Fifty consecutive eyes with anterior stromal disease suitable for DALK and 50 eyes with endothelial disease suitable for DMEK were scheduled for split cornea transplantation combining both procedures within 72 hours. Main outcome measures included success of using a single donor cornea for 2 recipients, best spectacle-corrected visual acuity (BSCVA), and complication rates within 6 months' follow-up.
A single donor cornea could be used for 2 recipients in 47 cases (94%). In 3 eyes (6%), the DALK procedure had to be converted to penetrating keratoplasty (PK) requiring a full-thickness corneal graft. Thereby, 47 donor corneas (47%) could be saved. Six months after surgery, mean BSCVA was 20/36 in the 47 eyes that underwent successful DALK, 20/50 in the 3 eyes that underwent conversion from DALK to PK, and 20/29 in the 50 eyes that underwent DMEK. Postoperative complications after DALK included Descemet folds in 5 eyes (11%) and epitheliopathy in 3 eyes (6%). After DMEK, partial graft detachment occurred in 26 eyes (52%) and was managed successfully with intracameral air reinjection. All corneas remained clear up to 6 months after surgery. No intraocular infections occurred.
Split use of donor corneal tissue for combined DALK and DMEK procedures in 2 recipients within 3 subsequent days is a feasible approach to reduce donor shortage in corneal transplantation in the future.
To review the published literature on deep anterior lamellar keratoplasty (DALK) to compare DALK with penetrating keratoplasty (PK) for the outcomes of best spectacle-corrected visual acuity (BSCVA), refractive error, immune graft rejection, and graft survival.
Searches of the peer-reviewed literature were conducted in the PubMed and the Cochrane Library databases. The searches were limited to citations starting in 1997, and the most recent search was in May 2009. The searches yielded 1024 citations in English-language journals. The abstracts of these articles were reviewed, and 162 articles were selected for possible clinical relevance, of which 55 were determined to be relevant to the assessment objective.
Eleven DALK/PK comparative studies (level II and level III evidence) were identified that compared the results of DALK and PK procedures directly; they included 481 DALK eyes and 501 PK eyes. Of those studies reporting vision and refractive data, there was no significant difference in BSCVA between the 2 groups in 9 of the studies. There was no significant difference in spheroequivalent refraction in 6 of the studies, nor was there a significant difference in postoperative astigmatism in 9 of the studies, although the range of astigmatism was often large for both groups. Endothelial cell density (ECD) stabilized within 6 months after surgery in DALK eyes. Endothelial cell density values were higher in the DALK groups in all studies at study completion, and, in general, the ECD differences between DALK and PK groups were significant at all time points at 6 months or longer after surgery for all of the studies reporting data.
On the basis of level II evidence in 1 study and level III evidence in 10 studies, DALK is equivalent to PK for the outcome measure of BSCVA, particularly if the surgical technique yields minimal residual host stromal thickness. There is no advantage to DALK for refractive error outcomes. Although improved graft survival in DALK has yet to be demonstrated, postoperative data indicate that DALK is superior to PK for preservation of ECD. Endothelial immune graft rejection cannot occur after DALK, which may simplify long-term management of DALK eyes compared with PK eyes. As an extraocular procedure, DALK has important theoretic safety advantages, and it is a good option for visual rehabilitation of corneal disease in patients whose endothelium is not compromised.
To describe Descemet's membrane endothelial keratoplasty (DMEK) techniques, perioperative challenges, management, and visual and refractive outcomes.
Prospective, multicenter, consecutive case series.
Sixty eyes of 56 patients with Fuchs' endothelial dystrophy, pseudophakic bullous keratopathy, or failed previous graft.
Descemet's membrane (DM) and endothelium were stripped from donor corneas submerged in corneal storage solution in a corneal viewing chamber. Donor DM diameters were 8.5 or 9.0 mm. The central 7 mm of DM was stripped from the recipient cornea. After staining with trypan blue to improve visualization, donor DM was inserted through a 2.8-mm incision. Descemet's membrane endothelial keratoplasty was performed alone (n = 48) or was combined with phacoemulsification and lens implantation (n = 11), pars plana vitrectomy (n = 2), or both.
Best spectacle-corrected visual acuity (BSCVA), manifest refraction, and endothelial cell density.
Median BSCVA was 20/30 at 1 month (range, 20/20-20/60), improving from 20/50 (range, 20/25-hand movements) before DMEK, excluding 4 eyes (7%) with preexisting ocular pathologic features that limited visual potential. At 3 months, 26% had 20/20 vision, 63% saw 20/25 or better, and 94% saw 20/40 or better. Refractive cylinder remained unchanged at 0.9 diopters (D; P = 0.93), and a hyperopic shift of 0.49+/-0.63 D (P = 0.0091) was noted in DMEK single procedures. Endothelial cell loss was 30%+/-20% at 3 months and 32%+/-20% in 38 eyes that reached the 6-month examination. Median pachymetry decreased from 660 mum before surgery to 530 mum. Descemet's membrane stripped successfully from 60 of 72 donor corneas; 6 were converted successfully to Descemet's stripping automated endothelial keratoplasty (DSAEK) and 6 (8%) were discarded. Only 1 graft detached completely, but air was reinjected in 38 eyes (63%), mainly for partial detachments. Five DMEK corneas (8%) failed to clear and were replaced successfully with DMEK or DSAEK. All remained clear at last follow-up.
Compared with DSAEK, DMEK provided a significantly higher rate of 20/20 and 20/25 vision, with comparable endothelial cell loss. Descemet's membrane endothelial keratoplasty restored physiologic pachymetry, but donor preparation and attachment currently are more challenging than with DSAEK.
We describe a lamellar keratoplasty technique to bare Descemet's membrane in which air is injected to detach the central Descemet's. After a partial-thickness corneal trephination is performed, a disposable needle is inserted, deeply and bevel down, into the paracentral corneal stroma and air is injected. In most cases, this forms a large air bubble between Descemet's membrane and the corneal stroma. After anterior lamellar keratectomy is performed, a small opening is made in the air bubble and the remaining stromal layers are lifted with an iris spatula, severed with a blade, and excised with scissors. This technique is faster, safer, and easier to perform than previous methods.
Recent advances in surgical technique have promoted a paradigm shift in the surgical treatment of corneal disease. Penetrating keratoplasty is now being replaced by various types of lamellar techniques that aim to replace damaged tissue only, while maintaining healthy tissue intact. This review focuses on recent advances in deep anterior lamellar keratoplasty.
The concept of creating a deep lamellar bed for lamellar keratoplasty is not new, but exposing Descemet's membrane was a tedious, time consuming procedure. New techniques that use air and ophthalmic viscosurgical devices to directly expose Descemet's membrane have dramatically reduced surgery time, while improving the safety of performing surgery. The indications for deep anterior lamellar keratoplasty have expanded from keratoconus and hereditary dystrophies, to include severe ocular surface disease and cases following infection and corneal perforation.
Deep anterior lamellar keratoplasty can be considered as the first choice of surgery for a wide range of corneal disease, with bullous keratopathy as the only absolute contraindication.
To describe the visual outcomes and intraoperative and postoperative complications after penetrating keratoplasty (PK), deep lamellar endothelial keratoplasty (DLEK), Descemet stripping endothelial keratoplasty (DSEK), and Descemet stripping automated endothelial keratoplasty (DSAEK) and to compare the results with those of previously reported series.
Prospective, comparative, nonrandomized study.
One hundred seventy-seven eyes of 161 consecutive patients who had corneal edema resulting from Fuchs endothelial dystrophy, pseudophakic bullous keratopathy, aphakic bullous keratopathy, failed graft or iridocorneal endothelial syndrome.
All patients underwent either PK, DLEK, DSEK, or DSAEK at the Cornea Service of the Toronto Western Hospital.
Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), manifest refraction, corneal endothelial counts, and postoperative complications.
The average 12-month postoperative BSCVA was 20/53 in the PK group, 20/80 in the DLEK group, 20/56 in the DSEK group, and 20/44 in the DSAEK group. The mean spherical equivalent was similar between groups, but tended toward hyperopia in the DSEK and DSAEK groups. The average refractive astigmatism was 3.78+/-1.91 diopters (D) in the PK group and 1.61+/-1.26 D, 1.86+/-1.1 D, and 1.36+/-0.92 D in the DLEK, DSEK, and DSAEK groups, respectively (P<0.0001). Early postoperative donor disc dislocations occurred in 6 (8.8%) patients in the DLEK group, 2 (12.5%) in the DSEK group, and 7 (15.6%) in the DSAEK group (P = 0.0004). Detached grafts were reattached and repositioned by injecting an air bubble to press the donor against the recipient cornea. Primary graft failure occurred in 1 (2.1%) of the PK cases, 2 (2.9%) of the DLEK cases, and 1 (2.2%) of the DSAEK cases; all underwent the same procedure successfully. Average cell loss at 1 year after surgery was 40.11% and was similar in the 4 groups.
The DSAEK surgery enabled rapid and better UCVA and BSCVA when compared with PK, DLEK, and DSEK, with significantly lower astigmatism. Endothelial cell loss was similar, but the dislocation rate was significantly higher in the DSAEK group.